Lubricating composition



3,028,335 LUBRICATING COMPUSITION Muthn Shamaiengar, Pittsburgh, Pa., assignor to Waverly Oil Works Company, a corporation of Pennsylvania No Drawing. Filed Oct. 20, 1958, Ser. No. 768,037 2 Claims. (Cl. 252-33.3)

,This invention relates to the art of lubricants and has particular relationship to lubricating compositions for cold rolling or cutting metals and for other metal working operations such as grinding, drawing, trimming and the like.

The above-listed metal working operations are characterized by the application of enormous pressures, shears or tensions to the metal being treated. For example, in cold rolling metal strip, the strip is passed between hardened steel rolls which exert suilicient pressure on the strip to deform it plastically. The rolls reduce the thickness of the strip at the same time elongating the strip but producing substantially no change in its Width. The pressure required to produce this thickness reduction depends on the material but is in any event very high. In high-speed tandem mills for cold rolling mild steel, the pressures are as high as 40,000 pounds per square inch and the temperatures are correspondingly high. The lubrication involved here is described as boundary lubrication and is commonly referred to as extreme-pressure, or EP, lubrication.

To the extent practicable, it is necessary that the friction between the treating mechanism and the metal be minimized. This maybe achieved by a film of a lubricant. But the extent to which the lubricating action may be applied is limitedsince there must be adequate adherence of the mechanism to the metal and excessive lubrication would cause slipping. The demand for adherence is particularly important in cold rolling of metal strip. If the lubricant permits slipping, chattering occurs as the rolls pass over the strip.

Another important requirement particularly in cold rolling of steel is that there be no reaction at the surface of the steel, at the high temperature and pressure, between the steel and the lubricant which would cause staining of the steel during the subsequent annealing operation.

In accordance with the teachings of the prior art, palm oil is used in metal working of the type just described. Palm oil usually includes a variable mixture of glycerides and different fatty acids. In cold rolling of steel the palm oil is applied differently for different thicknesses of the strip. While the strip is of heavier gauge the concentra tion of the palm oil is 100%. When thinner gauges of the order of 0.03 or 0.04 inch are reached, the lubricant is applied as an emulsion of 5% to palm oil and 95% to 90% water. In use the lubricant is sprayed under adequate pressure on the strip, the pressure rolls and the backup rolls as the thickness-reduction progresses.

Palm oil is available in the United States only as an import from such areas as South America. Because of the quantities in which it is used (for example, 40 million pounds between 1939 and 1949), it is desirable that a domestic lubricant be available and it is an object of this invention to provide such a lubricant.

It is a further object of this invention to provide a new lubricant for metal working which shall meet the confiicting requirements imposed -by metal working operations.

This invention is based on the recognition that effective lubrication is provided by a solid boundary film that possesses a closely packed strongly oriented structure. It was found that treatment of unsaponified triglycerides of fatty acid, such as animal fat, with ethylene polymers produced by subjecting ethylene to high pressure (750 to 1200 States ,l atefit pounds per square inch) and high temperatures (300 C. to 450 C.) or with parafiinic-base petroleum results in lubricants at least equal to, and in certain cases superior to, the available lubricants.

Specifically, an unsaponified triglyceride of a fatty acid, the source of which would be either animal or vegetable, is treated with sodium benzoate at a high temperature of the order of 270 C. to produce a gel-like substance which is then dissolved llll mineral oil. The use of unsaponified fat is a radical departure from prior art teaching in accordance with which a saponified fat serves as a base for a lubricant. The lubricant according to the invention has been found to have satisfactory properties to serve for metal working.

The lubricant according to this invention may be produced in different ways and with different components. A preferred process is the following:

(1) A mass of tallow is heated to 50 C. to melt the tallow.

(2) About 5% by weight of sulfonated castor oil is added and the mass is heated to about 140 C. and

stirred.

(3) About 2% by weight of sodium benzoate is added and the mass is stirred rapidly.

(4) The temperature of the resulting mass is then raised to about 280 C. to 290 C. and maintained at this temperature while specimens are removed from the mass and observed.

(5) When it is observed from the specimens that suspended particles of sodium benzoate have dissolved, a mass of mineral oil such as Eureka R mineral oil about 2 /2 times the weight of the tallow is added, and the temperature of the resulting mass is maintained at about 270 C. to 285 C. for about 10 minutes and then cooled to about C.

(6) About 0.1% by weight triethanolamine is added; the mass is stirred for about /2 hour at 100 C.

(7) About .005 by weight phosphoric acid is added and the mass again heated to 270 C. 1 Y

(8) The mass is cooled to about 95 C. and enough hexylene glycol added to reduce the viscosity of the mass to that of a thick symp-likesubstance. The temperature is then raised to about C. and the mass stirred vigorously.

(9), The mass is reheated to about 270 C.

(10) The mass is cooled to about 50 C. and drained into drums.

The components are mixed and treated in kettles preferablyof stainless steel. The kettles should be provided with adequate stirrers and with hoods for venting fumes. The heaters may be of any suitable type such as oil circulatory heaters. Pumps should be provided for transporting the hot oil from kettle to kettle.

The sulfonated castor oil speeds the reaction of the tallow and the sodium benzoate.

The Eureka R oil is a bright-stock petroleum oil.

' The triethanolamine is a surfactant which improves the emulsification of the lubricant when it is mixed with water for the lubrication of strip of small thickness in the rolling process. The high boiling temperature of the triethanolamine permits its use in the process.

The phosphoric acid imparts slightly acidity to the reaction. It appears that the lubricant should be slightly acid. The acid also improves the uniformity of the lubricant.

The hexylene glycol is a glycol with a hexyl group. The hexylene glycol serves to reduce the viscosity of the lubricant. it also serves to keep any unreacted mineral oil and fatty material in solution. Diethylene glycol may be used instead of he'xylene glycol.

a if The lubricant produced in practicing the above-described method has the following properties:

The lubricant was compared with a typical prior art lubricant in a precision shell four-ball extreme-pressure V lubricant torque tester following the method of the United States Steel Corporation.

In a four-ball tester a steel ball is supported rotatably on three locked steel balls in a cup containing the lubricant under test. The rotatable ball engages the fixed balls at bearing points. The locked balls are pressed by a loading force against the rotatable ball and the latter is rotated at a low speed of about .3 r.p.m. The friction between the rotatable ball and the locked balls at the bearing points manifests itself by the deflection of a recording stylus caused by the movement of a lever arm connected to the cup. The stylus produces a line on a chart the length of which is a measure of the torque produced by the cup and thus of the friction between the balls. This length is expressed in millimeters below and in the following tables.

The comparative tests were conducted with 100% lubricant. The torque measurement for the lubricant according to the invention was 8 to 9 millimeters and for the prior-art lubricant 18 to 22 millimeters. The lower torque measurements indicate a superior lubricant. For a lubricating emulsion consisting of 95% water and lubricant according to this invention the measurement was 9 to 11 millimeters.

In the case of certain lubricants in accordance with this invention phosphoric acid has a remarkable eflect in improving the lubricant. This was demonstrated by comparing relatively small quantities of the lubricant with and 7 without the acid in the four-ball tester.

LUBRICANT I The following components were charged in a stainless steel kettle:

4 pounds of commercial tallow 4 pounds of the ethylene polymer produced by applying high pressure to ethylene at a high temperature 2% by weight sodium benzoate 1.4% by weight sulfonated castor oil Measurements in Millimeters Duration of Testing in Seconds Test I Test II 27. chatter.

LUBRICANT II About 005% by weight phosphoric acid was added to a lubricant I and the resulting mass heated to about 150 C. to 175 C. for about hour and then allowed to cool. Samples for test were removed at about C.- C. and were tested in the four-ball tester at about 1,000,000 pounds per square inch and .3 rpm. The results were as follows for one test:

Duration of testing Measurement in seconds: in millimeters 10 200 10 300 10 400 11 500 12 600 12 700 13 800 13 900 14 LUBRICANT III About 2% by Weight phosphoric acid was added to lubricant I and the mass treated as in the case of lubricant II. The following results were obtained in testing a sample of lubricant III:

Duration, seconds: Measurement, mm.

It appears that an increase in the acidity does not improve the lubricant.

Lubricant II was also compared with a prior-art commercial lubricant in the four-ball tester at a pressure exceeding 1,000,000 pounds per square inch and at .3 rpm. The results were as follows:

Measurement-s, Mm. Duration, Seconds Lubricant II Commercial The lubricant in accordance with this invention is usually produced in substantial quantities with apparatus including two stainless steel kettles (hereinafter called kettle I and kettle II) each provided with hoods connected to an exhaust system, a suitable propeller agitating device and a steam chest. Cooling of the kettles can be efiected by letting water into the steam chest. The apparatus also includes an oil circulatory heater and two pumps having adequate capacity for handling the oil.

LUBRICANT IV (4) About pounds of parafiin-base mineral (Atlantic Refining Company) oil was added over a period of 30 minutes while stirring vigorously.

(5) Kettle I was connected to the oil circulatory heater and the thermostat of the heater set at 510 F. (265.6 C.). (The actual observed temperature of the mass was about 275 C.) The contents of the kettle was circulated through the heater for about 4 hours to react completely the benzoate, fat and oil. Samples were observed every /2 hour to determine the end point.

(6) The heater was stopped and the contents of kettle I transferred to kettle II and the contents cooled to about 63 C.

(7) About 1 pound of orthophosphoric acid was added.

(8) About 6.5 pounds of hexylene glycol was added and kettle II connected to the circulatory heater and the contents heated to 510 F. to 520 F. (265 C. to 271 C.).

(9) The resulting mass when found to be homogeneous was cooled to 120 F. (48.90 C.).

LUBRICANT V Another lubricant was produced as follows: (1) Same as lubricant IV. (2) About 5 pounds by weight of sulfonated castor oil was added and the kettle heated to 150 C.

(3) Same lubricant IV.

(4) About 2 /2 times by weight of mineral oil (based on initial charge of tallow) was added and contents were stirred hour.

(5) Same as 5 for lubricant IV except that the thermostat was set at 515 F. (268.9 C.).

( 6) Same as for lubricant IV.

7) About .1% by weight of triethanolamine was added while stirring vigorously.

(8) About .004% of phosphoric acid was added and the mass heated to 510 F. to 520 F. (265 C. to 271 C.) for 15 minutes.

(9) The mass was cooled to 200 F. (93.3 C.).

(10) About 2% by weight (based on the net weight of tallow and mineral oil) of hexylene glycol was added and the mass heated to 510 F. (265 C.) slowly and kept at the latter temperature minutes.

(11) Same as 9 for lubricant IV.

Lubricants IV and V were evaluated in a laboratory rolling mill of Allegheny Refining Company of Verona, Pennsylvania. This is a two high mill with the rolls 4 inches in diameter and 6 inches wide. The strip rolled was partially work hardened 1010 steel .250" x .0063". The rolls revolved at a surface speed of about 200 ft. per minute in one test and 1000 ft. per minute in the other test. A test was also run with a commercial lubricant. The tests were run both with the strip precoated with a thin coating of lubricant about one microinch thick and with the strip precoated with a heavy coating of lubricant which is run off. The precoated strip was fed to the rolls through a trough through which a stream of emulsion consisting of 95 water and 5% lubricant was flowing.

The following data was derlved:

Load Exct. Coefli- Lubricant Method of Apply- Lb. Gauge cient of ing Lubricant Vertiin Friction cally inches of Rolls Suspension only... 3, 480 0044 043 Thin Preeoat 3, 400 .0040 .033 Suspension only... 4, 220 .0033 035 Thin Precoat 4, 200 .0031 .032 Suspension only-.. 3, 440 0043 .041 Heavy Precoat..-. 3, 400 .0038 .030 Suspension only... 4, 220 .0033 .035 Thin Precoat 4, 200 .0031 032 Suspension only-.. 3, 460 .0043 040 Thin Preeoat 8, 380 0039 030+ Suspension only.-- 4, 220 .0033 .035+ Thin Precoat 4, 200 0032 .033

Evaluated in the four-ball tester with 1,000,000 pound per squareinch pressure and at .3'r.p.m., lubricants IV and V gave the following results:

LUBRICANT IV Measurement in mm.

Duration of Testing in 100% water -5% Lub.

Seconds Lub.,

Room 60 0 Temp. Room 60 0.

Temp.

8 9 9 13 8 8 9 l3 8 8 9 ll 8 8 9 l1 8 8 11 11 8 8 11 ll 8 8 11 ll. 8 8 11 11 LUBRICANT V 95% water5% lubricant Duration of testing: Measurement in mm. 7 200 7 300 7 400 7 500 7 600 7 700 7 800 7 900 7 While preferred embodiments of this invention have been disclosed herein many modifications thereof are feasible. This invention then is not to be restricted except insofar as is necessitated by the spirit of the prior art.

I claim as my invention:

1. The method of making a lubricant particularly for metal working consisting essentially of adding about 2% by weight of sodium benzoate and about 5% by weight of 75% sulfonated castor oil to a mass of liquified unsaponified triglyceride of a fatty acid, adding to said mass mineral oil having a weight of one to about two and onehalf times the weight of said triglyceride, heating the sodium benzoate, triglyceride, sulfonated castor oil and mineral oil to a temperature of about 270 centigrade to produce a solution of said triglyceride and benzoate in said oil, and adding to said solution a small quantity of about .005% by weight of the solution of phosphoric acid.

2. The lubricant made by the process defined in claim 1.

References Cited in the file of this patent UNITED STATES PATENTS 2,207,256 Kapp July 9, 1940 2,328,727 Langer Sept. 7, 1943 2,422,075 Bray June 10, 1947 2,43 0,400 Hoelscher Nov. 4, 1947 2,470,913 Bjorksten et a1 May 24, 1949 2,732,345 Kroenig et a1 Ian. 24, 1956 2,846,393 Cook et al Aug. 5, 1958 FOREIGN PATENTS 689,739 Great Britain Apr. 1, 1953 OTHER REFERENCES Bastian: Metalworking Lubricants, 1951, McGraw- Hill, pages ll, l4, l6 and 17. 

1. THE METHOD OF MAKING A LUBRICANT PARTICULARLY FOR METAL WORKING CONSISTING ESSENTIALLY OF ADDING ABOUT 2% BY WEIGHT OF SODIUM BENZOATE AND ABOUT 5% BY WEIGHT OF 75% SULFONATED CASTOR OIL TO A MASS OF LIQUIFIED UNSAPONIFIED TRIGLYCERIDE OF A FATTY ACID, ADDING TO SAID MASS MINERAL OIL HAVING A WEIGHT OF ONE TO ABOUT TWO AND ONEHALF TIMES THE WEIGHT OF SAID TRIGLYCERIDE, HEATING THE SODIUM BENZOATE, TRIGLYCERIDE, SULFONATED CASTOR OIL AND MINERAL OIL TO A TEMPERATURE OF ABOUT 270* CENTIGRADE TO PRODUCE A SOLUTION OF SAID TRIGLYCERIDE AND BENZOATE IN SAID OIL, AND ADDING TO SAID SOLUTION A SMALL QUANTITY OF ABOUT .005% BY WEIGHT OF THE SOLUTION OF PHOSPHORIC ACID. 